Title: Confirmation of Homologous Strains as the Cause of Bacillary Dysentery Outbreaks in Miaoli County an
1Confirmation of Homologous Strains as the Cause
of Bacillary Dysentery Outbreaks in Miaoli County
and Taichung County by Molecular Epidemiology
- Tsuey-Fong Lee
- Centers for Disease Control, Taiwan
2Shigellosis in Taiwan
- 30-50 cases annually
- 90 caused by S. sonnei
- Outbreak in mountainous areas
Miaoli County
Taichung County
3Index case of shigellosis in Miaoli County
- Reported on November 26, 2005
- 9-year-old girl from Nanjhung Township
- Onset on November 18, 2005
- Symptoms included diarrhea, abdominal pain,
fever, and headache - S. sonnei isolated from stool
- Did not travel out of the country in the 3 months
prior to illness
4Miaoli County outbreak
- Cases discovered in Nanjhung Township
- Dong Village, Si Village, Nanjiang Village,
Dongho Village - Diarrhea cases 23
- S. sonnei positive cases 11
- Age range (years) 3-77
- Symptom onset Nov 18-Dec 5, 2005
- Asymptomatic case 1
5Index case of shigellosis in Taichung County
- Reported on January 14, 2006
- 7-year-old boy from Heping Township
- Onset on January 7, 2006
- Symptoms included diarrhea, abdominal pain,
fever, and headache - S. sonnei isolated from stool
- Did not travel out of the country in the 3 months
prior to illness
6Taichung County outbreak
- Cases discovered in Heping Township
- Diarrhea cases 14
- S. sonnei positive cases 5
- Age range (years) 7-59
- Symptom onset January 7-17, 2006
7Geographic distribution of confirmed cases (n37)
8Objectives
- Use pulsed-field gel electrophoresis (PFGE) to
explore the relationship between the two
outbreaks - Compare PFGE patterns with the Shigella DNA
fingerprint database of the Taiwan CDC to trace
the origin of the bacteria
9Epidemiological investigation
- Index cases and there close contacts
- Family members
- School classmates
- Local clinical doctors
- Neighbors
- Foreign members
- Diarrhea patients with relevant travel histories
10Case definition
- Confirmed ?2 diarrheal episodes/day, positive
for Shigella - Suspected diarrhea, negative for Shigella
- Asymptomatic case no diarrhea, positive for
Shigella
11Environmental investigation
- Water taken from
- Residences
- School
- Water tested for
- Residual chloride
- Bacteria
12Laboratory examination
- Rectal swabs and water were collected for
bacterial isolation and identification - PFGE pattern analysis and comparison
- Using standardized PulseNet method developed by
US CDC - PFGE pattern were analyzed by BioNumerics
- Compared with Taiwan CDC Shigella DNA fingerprint
database
13Shigellosis outbreaks in Miaoli and Taichung
counties 11/18, 2005-1/23,2006
Miaoli county n23
Taichung county n14
14Epidemiological relationship for the Miaoli
County outbreak
11/23/05
15Epidemiological relationship for the outbreak in
Taichung County (n14)
16Epidemiological relationship in Miaoli and
Taichung County, 20052006
Heping Township
Nanjiang Village
1/12/06
Homeroom teacher
11/23/05
11/27/05
1/8/06
Asymptomatic case
.
11/26/05
11/29/05
Index case 2
11/26/05
Class A
11/27/05
11/26/05
1/7/06
1/7/06
1/17/06
Family
School X
Family
17Rectal swab examination
18Water specimens examination
19The dendrogram of PFGE fingerprints
Strains No
PFGE genotype
Township
County
year
Miaoli
Nanjhuang
Miaoli
Nanjhuang
Nanjhuang
Miaoli
Nanjhuang
Miaoli
Miaoli
Nanjhuang
Nanjhuang
Miaoli
Miaoli
Nanjhuang
Miaoli
Nanjhuang
Miaoli
Nanjhuang
Strain from Indonesia, 2005
Miaoli
Nanjhuang
Miaoli
Gonggung
Taichung
Heping
Heping
Taichung
Taichung
Heping
Taichung
Heping
Taichung
Heping
Taipei
Jhongsham
Miaoli
Nanjhuang
Miaoli
Nanjhuang
Miaoli
Nanjhuang
Miaoli
Nanjhuang
Miaoli
Nanjhuang
Taichung
Cingshuei
20Discussion
- Study demonstrated value of Shigella DNA
fingerprint database - Compare and trace strains
- Investigate the mode and route of transmission
- Monitor disease status
- Share information with international disease
prevention organizations
21Conclusion
- Water contamination excluded in both outbreaks
- Resulted from human-to-human transmission
- The strains in the outbreak in Taichung County
was from Mioali County - Strains in the two outbreaks might have
originated from Indonesia
22Recommendation
- Enhance international cooperation
- Establish international information database
23Acknowledgment
- Health Bureaus of Miaoli County and Taichung
County - Members of the FETP
- We-Gong Hospital and Fong-Yen Hospital
24Thank you for your attention